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<h3> Web100 based Network Diagnostic Tool (NDT) </h3>
<br><font size=-1>
This java applet was developed to test the reliablity and operational
status of your desktop computer and network connection.  It does this by sending data between your
computer and this remote NDT server.  These tests will determine:</font>
<ul>
 <li><font size=-1>The slowest link in the end-to-end path (Dial-up modem to 10 Gbps Ethernet/OC-192)</font>
 <li><font size=-1>The Ethernet duplex setting (full or half);</font>
 <li><font size=-1>If congestion is limiting end-to-end throughput.</font>
</ul>
<br><font size=-1>
It can also identify 2 serious error conditions:</font>
<ul>
 <li><font size=-1>Duplex Mismatch</font>
 <li><font size=-1>Excessive packet loss due to faulty cables.</font>
</ul>
<br>A test takes about 20 seconds.  Click on "start" to begin.

<!-- this applet will email results to the person specified by the 
     param parameters.  The 'H' value is the hostname, the 'U' value
     is the username.  The 'subject' line overwrites the default message
     built into the java program.  -->

<table align=center><tr><td>
<applet code=edu.internet2.ndt.Tcpbw100.class ARCHIVE="Tcpbw100.jar,lib/json-simple-1.1.1.jar"
   width=700 height=320>
<!--
  <PARAM NAME="H" VALUE="ncren.net">
  <PARAM NAME="U" VALUE="throck">
  <PARAM NAME="subject" VALUE="NDT issue">
-->
</applet>
</td></tr></table>

<br>
<a href="mailto:ndt-users@internet2.edu?subject=Reporting NDT Issue
&amp;body=Your name:  %0aEmail:  %0aHostname:  %0a%0aPaste results from%20
'Statistics' window here:%0a%0a%0aPaste results from 'More Details' window%20
here:%0a%0a%0aComments:%0a">Report Problems</a> <font size=-1> &nbsp; &nbsp; &nbsp; &nbsp; Use "ctrl-C"
to copy data onto the clipboard and then paste it into the email message. </font>

<hr size=3  width="99%" noshade>
<br>
<p>The NDT performs 2 TCP throughput tests between your desktop
computer and this NDT server.  First, data is streamed for 10 seconds from your 
desktop to the server and then a second 10 second test is performed in the
opposite direction.  A <a href="http://www.web100.org">Web100</a> modified linux kernel
captures detailed statistics on these TCP data flows.  This data is then analyzed to
determine why the connection achieved the throughput results it reported.
<p>
<h3> Understanding the test results </h3>
<p>
End-to-End performance depends upon a number factors.  One of the biggest factors
is setting the tunable network parametes to the proper value.  There are several
web sites that provide detailed tuning instructions for various Operating Systems.
Two of the best are:
<ul>
<li)<a href=http://www.psc.edu/networking/projects/tcptune>PSC's Enabling High
Performance Data Transfers</a>
<li><a href=http://dsd.lbl.gov/TCP-tuning>LBNL's TCP Tuning Guide</a>
</ul>
The throughput an application achieves is dependant on the amount of buffer space
available in the sending and receiving hosts, packet loss due to errors or congestion,
packet size (usually limited to 1500 bytes by Ethernet), and the round trip time
between the 2 hosts.  If this test reports that the sender or receiver buffer size
is the limiting factor, increase the buffer size by 
<a href="http://www.psc.edu/networking/perf_tune.html">changing the default buffer size</a>
on your computer.  Win 95/98/NT users can easily set and change their default buffer size
by using the <a href="http://moat.nlanr.net/Software/TCPtune/">TCPtune application</a>
developed by the NLANR MOAT group.  Windows users may find that they perfer the
<a href="http://www.dslreports.com/front/drtcp.html">DrTCP</a> tool from the dslreports.com
web site.  
<p>
If a large number of retransmissions occur,
check the duplex and speed setting on your host and the network switch it attaches
to (duplex mismatches are a serious problem due to broken autonegoation protocols).
Extremely long round trip times (over 1 sec) ususally indicate that a network router
or switch is congested leading to long queuing times.  Contact your local network
administrator for help in solving this problem
<p>
The Bandwidth * Delay product is reported at the bottom of the "more details" page.
Throughput limits for the NDT server's transmit buffer, your clients receive buffer,
and the network infrastructure.  You may use these numbers as a guide to determining
what your client's receive buffer is currently set to.  Divide the buffer size by
the reported round trip time (RTT) to calculate the throughput value.
<p>
For more info on TCP tuning, visit
<a href="http://cable-dsl.home.att.net/"> cable/dsl tuning</a>
or dslreports.com <a href="http://www.dslreports.com/tweaks/">tweaks</a>
or <a href="http://www.psc.edu/networking/perf_tune.html">UNIX and
Windows TCP/IP tuning tips</a>.
<p>
You can find the Web100 variables descriptions gathered on the following <a href="web100variables.html">web page</a>.
<hr width="95%" noshade>
<h3>REN accessable NDT servers:</h3>
<p>A list of servers known to the Researh and Education Network (REN) community is
   located on the <a href="http://e2epi.internet2.edu/ndt/ndt-server-list.html">Internet2
   e2epi web page</a>.  Note: that not all of these REN servers will be publicly
   accesible.
<h3>Other publicly accessible NDT servers:</h3>
<ul>
<li><a href="http://ndt.anl.gov:7123">Argonne National Laboratory - IL (USA)</a>
<li><a href="http://ndt.switch.ch">Swiss Education and Research Network (Switzerland)</a>
<li><a href="http://web100.rit.edu:7123">Rochester Institute of Technology - Rochester NY (USA)</a>
<li><a href="http://speedtest.umflint.edu">University of Michigan - Flint MI (USA)</a>
<li><a href="http://nitro.ucsc.edu/">University of California - Santa Cruz CA (USA)</a>
<li><a href="http://netspeed.stanford.edu/">Stanford University - Palo Alto CA (USA)</a>
<li><a href="http://jlab4.jlab.org:7123">Thomas Jefferson National Accelerator Facility - VA (USA)</a>
<li><a href="http://ciseweb100.cise-nsf.gov:7123">National Science Foundation - VA (USA)</a>
</ul>
<br><br>
<h3>Other bandwidth testing sites:</h3>
<ul>
<li>microsoft's bandwidth <a href="http://www.msn.zdnet.com/partners/msn/bandwidth/speedtest.htm"> tester</a>
<li> <a href="http://www.dslreports.com/tools"> upload/download tester</a>
<li> <a href="http://www.browsertune.com/bt2kfast/">bt2kfast</a> 
<li> <a href="http://www.dslreports.com/stest/0">www.dslreports.com speed test</a>
browser/throughput tester
<li> <a href="http://whisper.cs.utk.edu:7123">UT web100 bandwidth tester</a>,
 experimental (not always available)
<li> the older ORNL java
 <a href="http://www.epm.ornl.gov/~dunigan/java/misc/tcpbw.html">
 bandwidth tester</a>
</ul>
<p>
You can see the hops (routers) that your packets pass through from
your machine to a target Internet site with the <i>traceroute</i> command
(for Windows, use <i>tracert</i> in DOS/command prompt window).
The route can actually vary from packet to packet, test to test,
and the reverse route (return path) may not be the same.
There are several
<a href="http://www.slac.stanford.edu/comp/net/wan-mon/traceroute-srv.html">
traceroute servers</a> around the world that can show you the
route back to your browser.
Tom Dunigan at ORNL also has traceroute servers at
<a href="http://www.epm.ornl.gov/~dunigan/cgi-bin/traceroute.cgi">ORNL</a>
and at <a href="http://www.cs.utk.edu/~dunigan/cgi-bin/traceroute.cgi">UT</a>.

<p>
The NDT server window size for this Java tester is 64KB.
Max window used to be 64KB, but newer OS's now support window scaling,
so you may be able to request more than 64 KB.
(This NDT server a window of 64,000 bytes,
and the network interface is 100 Mbs.)
<p>

The NDT software (source and compiled programs) is available via the Internet2
End2End Performance Initiative web server
at <a href="http://e2epi.internet2.edu/ndt/download.html">e2epi.internet2.edu/ndt/download.html</a>. 
You can also learn more about the NDT system by subscribing to the 
<a href="https://mail.internet2.edu/wws/info/ndt-users">NDT user discussion</a>
or <a href="https://mail.internet2.edu/wws/info/ndt-announce">NDT announcement</a>
lists hosted by Internet2.  
<p>
This java applet was originally developed by ORNL and has been extensively modified
at ANL.
<br>
Complete University of Chicago <a href="copyright.html">Copyright Notice</a>
<hr noshade width="90%" size=-4>
Comments to <a href="mailto:RCarlson@internet2.edu"> Rich Carlson </a> email:RCarlson@internet2.edu
<br><i>Created: April 4, 2002 by Rich Carlson
<br>Last Updated: June 8, 2005 by Rich Carlson </i>
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